This invention relates generally to the field of electronic chassis that house electronic components to be used in, as an example, high-speed telecommunication and networking applications. In particular, the present invention relates to a method and apparatus for monitoring electrical connector degradation in such an electronic chassis by counting the number of insertions experienced by a circuit board to a backplane connector or the like.
An electronic chassis that houses electronic components for high-speed telecommunication and networking applications typically includes a plurality of circuit board assemblies. Some of these circuit boards may be referred to as application cards and perform various functions such as digital signal processing. These chassis are often referred to as a high availability platform due to the fact that the chassis are designed for continuous operation. Individual application cards may be inserted and removed for maintenance and other reasons.
The chassis includes a backplane circuit board including various connectors typically fastened to the pair of card guide assemblies. The backplane circuit board forms the back wall of the chassis. When the application cards are inserted into the chassis they are guided into the chassis along a pair of card guide assemblies mounted between the sidewalls of the chassis. One of the card guide assemblies is typically located adjacent the top of the chassis and the other is typically located adjacent the bottom of the chassis. When fully inserted into the chassis, connectors located along the back edge of the application cards are connected to the connectors located on the backplane circuit board. These connectors may be referred to as backplane connectors.
While a variety of electrical backplane connectors are known in the art, all such connectors interconnect circuit boards to a backplane or motherboard to daughterboard. For purposes of this application, backplane connectors will be considered to include a male portion including a plurality of conductive pins or the like, which conduct electrical power or signals. A female portion is typically associated with the application card. The female portion is sized and shaped to receive the male portion while providing proper alignment of the two portions and providing electrical connection with the pins. Other arrangements of the connector portions are contemplated.
As connection densities increase there is an increasing focus on providing a reliable manner of interconnecting a large number of densely organized printed circuit board pads to a connector of minimal size while still providing a high degree of reliability. These types of connectors may suffer failures or reduced reliability resulting from stresses applied to the connectors from insertion and removal of the printed circuit board.
Such electrical connectors often specify useful life expectancy in terms of the number of mates that can be made reliably. Accordingly, there is a demand for a method and apparatus to monitor the degradation of backplane connectors by generating and providing insertion information, such as an insertion count (mates) to a management entity. The present invention satisfies this demand.
It is an object of the present invention to generate and provide insertion count information with respect to chassis based platforms or like systems where a large number of densely organized printed circuit boards or application cards are employed and connected to the host system by backplane connectors, for example. In such a system, for maintenance and other purposes, the cards may be removed from the backplane connector a number of times during the lifecycle of the card. In order to monitor the effective remaining useful life of an individual connector on the card, it is an object of the invention to generate, store and report data related to the number of times that a particular card has been removed and inserted into the slot of the backplane connector.
Briefly, the invention relies on an insertion monitor circuit to indicate a connector mate. During the power up sequence of an application card, the insertion monitor makes use of physically staggered terminals or pins on an application card being connected to a backplane connector in a specified mating sequence to identify an insertion event. The staggered arrangement of pins guarantees the mating sequence in a predetermined order.
With respect to the insertion monitor circuit, in one embodiment of the invention, hardware resource bus (HRB) power pin(s) make electrical connection to a backplane connector prior to a single sense line. It may be assumed in this embodiment that a digital ground is already connected. In another embodiment, the HRB pin makes electrical connection to a backplane connector prior to two sense lines. In this embodiment, both sense lines must be grounded before the sequence is completed. This sequence first provides power to the insertion monitor circuit and provides voltage to sense resistor pull-ups of the card. Subsequent to contact of the HRB pins, one or more sense pin is mated to the backplane connector. As a result, the sense pins are grounded on the backplane. This causes the circuit to transition from a high voltage to a low voltage. This transition from a high state to a low state is detected by the circuit and used to indicate an insertion.
Either a single sense line may be used or a combination of two or more spaced sense lines. In the event that two independent sense lines are used, the lines are physically spaced on opposite ends of the card so as to ensure complete seating of the card with the connector before the insertion detection occurs. In this case, both sense lines are required to become grounded before the circuit completes the transition and an insertion count is subsequently incremented. Further, a debounce circuit, as known in the art, may be used to reduce errors during mating of the card. The debounce circuit is used to produce a single transition of the state of the card when inserting the card. Without a debounce circuit, it is possible to see multiple transitions on the insertion detection circuit. Debouncing is common when interfacing electronics to mechanical systems. In one example of a debounce circuit, a timer is used, which requires that both sense lines are grounded for a predetermined length of time before subsequent next steps occur in the process of indicating an insertion.
In the event that the insertion detection device detects a transition from a high state to a low state, a state device reads the contents of a non-volatile storage device (for example, EPROM, EEPROM and FLASH) to obtain the current insertion count value, updates the insertion count value by incrementally adding to the count value and writes the updated incremented count value to the non-volatile storage device.
It will be understood that the insertion detection circuit may include a hardware device or a combination of hardware and software. One example of a hardware device around which the insertion detection circuit may be implemented is a programmable logic device (PLD).
The advantage of using staggered terminals or pins is that the resulting sequence allows for differentiation between card insertion, and chassis power up. While it is assumed that a high-availability chassis is rarely powered off, the act of powering a chassis on and off will not be counted as an insertion event if the staggered pins are used to sense insertion. This is because after insertion, the sense lines are already mated to the connector when the chassis is powered off. When the chassis is subsequently powered up, the backplane holds the insertion sense lines low, and a transition from a high state is not seen on the sense lines or detected by the insertion detection circuit. Accordingly, no change in status is noted and an insertion count is not incremented.
In one embodiment of the invention, an insertion detection/state device/EEPROM can all be powered off hardware resource bus (HRB) power, or segmented so that only the insertion detection is powered by the HRB. This could be done if the state device was implemented in software. Such an embodiment assumes the user does not insert and remove application cards and the like from the chassis while the chassis is un-powered.
In another embodiment of the invention, a power source separate from the power supplied by the chassis, such as a battery or a charged capacitor (or a combination thereof) is positioned on the card to provide a power source independent from the chassis power. The independent power source provides the power to maintain the card at a high state even when the card is separate from a chassis. When the card is inserted, the card is grounded and the circuit transitions to a discharged (low) state and as a result the counter is incremented even if the chassis is powered off.
One aspect of the present invention provides a card monitoring apparatus for detecting and incrementing insertion counts of an application card to a backplane connector including a card connector positioned on the application card including connector terminals sized and shaped to be connected to the backplane connector. An insertion monitoring circuit is connected to a subset of the connector terminals for detecting an insertion of the application card into the backplane connector and generating and storing an insertion count therefrom.
Other aspects of the present invention provide a subset of connector terminals that may include a first conductor positioned on the application card for providing power to at least the insertion monitoring circuit and a second conductor positioned on the application card. The second conductor is electrically connected to the insertion monitoring circuit wherein the first conductor and the second conductor are offset with respect to each other such that during connection of the card connector to the backplane connector an insertion sequence is performed wherein the first conductor makes electrical contact or mates with the backplane connector before the second conductor. The insertion sequence is detected by the insertion monitoring circuit, which generates an incremental increase in the insertion count.
The monitoring circuit may include an insertion detection device for detecting the insertion of the card connector into the backplane connector. The insertion detection device may generate an insertion signal when an insertion is detected. The insertion monitoring circuit may include a state device connected to the insertion detection device for receiving the insertion signal and performing an update of the insertion count thereby. The insertion detection circuit may include a non-volatile memory device connected to the state device. The insertion count may be stored in the non-volatile memory device. The second conductor may include a first sense line and a second sense line. The card monitoring apparatus may further include one or more pull up resistors connected to the first conductor. The insertion detection device may include a multi-input OR gate with each OR gate input connected to a corresponding one of the first and second sense lines. The OR gate includes binary output corresponding to a first state indicating a high voltage in one of the first and second sense lines and a second state indicating a low voltage in the first and second sense lines. The first conductor may be a hardware resource bus terminal.
In the alternate, it will be appreciated that an AND gate may be substituted for the OR gate, whereupon only one of the first and second sense lines would be required to transition from a high state to a low state for the circuit to detect an insertion.
Another aspect of the present invention provides a line card for use in a high availability chassis connectable thereto by a backplane connector including a connector sized and shaped to connect to the backplane connector. The connector includes a plurality of connector terminals for transmitting electrical power and electrical signals, a subset of the plurality of connector terminals being connected to an insertion monitoring circuit of the line card. The insertion monitoring circuit includes a power conductor connected to a first terminal of the subset. One or more pull up resistors are connected to the power conductor. One or more sense lines are connected to respective one or more second terminals of the subset. The first terminal is positioned on the line card so as to be connectable to the backplane connector before the one or more second terminals. An insertion detection device is provided for detecting an insertion of the line card. A state device is connected to the insertion detection device for calculating a primary insertion count from the detection of the insertion and a non-volatile memory device is connected to the state device for storing the primary insertion count.
Other aspects of the present invention provide pull up resistors for holding the insertion monitoring circuit in a high state when the first terminal is inserted into the backplane connector. The one or more sense lines may permit the insertion monitoring circuit to transition to a low state when both of the one or more sense lines are inserted into the backplane connector. The insertion detection device may detect the transition from the high state to the low state and generates an insertion signal therefrom. The state device receives the insertion signal from the insertion detection device, reads a stored primary insertion count from the non-volatile memory device, incrementally increases the primary insertion count to produce an updated primary insertion count and writes the updated primary insertion count to the non-volatile memory device.
Another aspect of the present invention provides a system for monitoring the connection of an application card to a backplane connector of a host system, including a male connector connected to the host system. A female connector is provided to the application card and is sized and shaped to connect to the male connector. An insertion detection device is connected to the female connector for detecting an insertion connection between the female connector and the male connector and generating and storing an insertion count therefrom. A plurality of conductive terminals extend from the female connector for electrical communication with the backplane connector including a first conductor positioned on the application card for providing power to at least the insertion detection device and a second conductor positioned on the application card electrically connected to the insertion detection device. The first conductor and the second conductor are offset with respect to each other such that during mating of the application card to the backplane connector an insertion sequence is performed wherein the first conductor connects to the backplane connector before the second conductor. The insertion sequence causes an incremental increase in the insertion count.
Another aspect of the present invention provides a card monitoring apparatus for detecting and incrementing insertion counts of a line card to a backplane connector in a host system including a card connector positioned on the line card including connector terminals sized and shaped to be connected to the backplane connector and an insertion detection circuit connected to a subset of the connector terminals for detecting an insertion of the application card into the backplane connector and calculating and storing an insertion count therefrom.
Another aspect of the present invention provides a host system including a plurality of line cards. Each of the plurality of line cards includes a monitoring apparatus for detecting and incrementing insertion counts to one of a plurality of backplane connectors of a high availability chassis of the host system. Each of the plurality of line cards includes a card connector with connector terminals sized and shaped to be operably connected to one of the plurality of backplane connectors. The monitoring apparatus includes an insertion detection circuit connected to a subset of the connector terminals for detecting an insertion of a corresponding one of the plurality of line cards with one of the plurality of backplane connectors and determining and storing an insertion count therefrom.
Another aspect of the present provides a method of monitoring an insertion count of a line card to a backplane connector including providing the line card with an insertion monitoring circuit for detecting, incrementing and storing the insertion count. A first terminal of the insertion monitoring circuit is connected to the backplane connector to produce a high state. A second terminal, which may be two independent terminals, of the insertion monitoring circuit is connected to the backplane connector to transition the high state to a low state. The transition to the low state is detected. A current primary insertion count is retrieved in response to the detection of the transition. The current primary insertion count is incremented to produce an updated primary insertion count and the updated primary insertion count is stored as the current primary insertion count.
Further aspects of the method of the present invention may include providing the current primary insertion count to a management entity for monitoring purposes. The line card insertion monitoring circuit may be provided with an error detection and correction device and method.
In an alternate embodiment, and using the same set of staggered pins and electronic components as set forth herein, the same objective of incrementing an insertion count can be accomplished during removal of an application card. In this embodiment, it is contemplated that the detection device can be provided the capability of detecting an insertion by monitoring the sense lines. In the event that the value of the sense lines transitions from a low to a high value, the counter is incrementally increased. It will be appreciated that this must be done before the card loses power. In the alternate, the card may be provided with an onboard power source, such as a battery or capacitor or a combination thereof, for powering the components which detect, and increment the insertion count.
The invention provides the foregoing and other features, and the advantages of the invention will become further apparent from the following detailed description of the presently preferred embodiments, read in conjunction with the accompanying drawings. The detailed description and drawings are merely illustrative of the invention and do not limit the scope of the invention, which is defined by the appended claims and equivalents thereof.